Positioning means for camshaft roller bearing

ABSTRACT

A roller bearing assembly includes a plurality of rollers ( 122 ), a cage ( 114 ) including a plurality of slots ( 118 ) for positioning the plurality of rollers, an outer race ( 134 ) positioned radially outside the plurality of rollers and the cage, and means ( 126,130,138 ) for retaining axial alignment between the cage and the outer race provided integrally with at least one of the cage and the outer race.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/977,111 filed on Oct. 3, 2007, the entire contents of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a roller bearing, which may be used tosupport the camshaft of an internal combustion engine for rotation aboutan axis. More particularly, the invention relates to means formaintaining positive axial positioning of the roller bearing, andcomponents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art roller bearing assembly fora camshaft.

FIG. 2 is a cross-sectional view of the prior art roller bearingassembly, taken along line 2-2 of FIG. 1, illustrating the rollerbearing in a misaligned position.

FIG. 3 is a perspective view of a needle roller bearing cage of oneembodiment of the present invention.

FIG. 4A is a perspective view of a needle roller bearing assemblyincluding the needle roller bearing cage of FIG. 3 assembled with anouter race.

FIG. 4B is a cross-sectional view of the needle roller bearing assembly,taken along line 4-4 of FIG. 4A.

FIG. 5 is a cross-sectional view of the needle roller bearing assemblyof FIGS. 4A and 4B assembled on a camshaft.

FIG. 6A is a perspective view of a needle roller bearing assembly of oneembodiment of the present invention.

FIG. 6B is a cross-sectional view of the needle roller bearing assembly,taken along line 6-6 of FIG. 6A.

FIG. 7 is an end view of a needle roller bearing assembly of oneembodiment of the present invention.

FIG. 8A is a perspective view of a needle roller bearing cage of oneembodiment of the invention.

FIG. 8B is an alternate perspective view of the needle roller bearingcage of FIG. 8A.

FIG. 9A is a perspective view of a needle roller bearing assembly of oneembodiment of the invention assembled on a camshaft having a large axialspacing between cam lobes.

FIG. 9B is a cross-sectional view of the needle roller bearing assemblyand camshaft, taken along line 9-9 of FIG. 9A.

FIG. 10A is a perspective view of a needle roller bearing assembly ofone embodiment of the invention assembled on a camshaft.

FIG. 10B is a cross-sectional view of the needle roller bearingassembly, taken along line 10-10 of FIG. 10A.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate a prior art needle roller bearing assembly 20supporting a camshaft 24 between two axially adjacent lobes 28, 30 ofthe camshaft 24. The needle roller bearing assembly 20 includes a cage34, an outer race 38, and a plurality of needle roller elements 40.Commonly, an inner race can also be provided so that the needle rollerelements 40 do not directly touch the camshaft 24. In FIGS. 1 and 2, theneedle roller bearing assembly 20 is held within a two piece clamp-typeblock 42. The block 42 maintains the needle roller bearing assembly 20in a predetermined position, coaxial with the camshaft 24 such that theneedle roller bearing assembly 20 provides a low friction restrainingmechanism for the camshaft 24 to rotate in place (e.g., within thecylinder head of an internal combustion engine).

In the arrangement of FIGS. 1 and 2, the outer race 38 is clamped in theblock 42 and does not rotate with the camshaft 24. The needle rollerelements 40 contact the outer surface of the camshaft 24 (when aseparate inner race is not provided, as illustrated) and experiencerolling engagement therewith. The prior art outer race 38 is of a simplecylindrical form and as such, is free to move axially relative to theneedle roller elements 40 and the cage 34. The clamping of the outerrace 38 by the block 42 provides some resistance to axial movement ofthe outer race 38, but such movement is not inherently prevented, andthe initial installation of the needle roller bearing assembly 20 in theblock 42 is complicated by the lack of any intrinsic means forpositively axially positioning the needle roller bearing assembly 20relative to the block 42. FIG. 2 illustrates the case in which the cage34 is substantially sandwiched between the adjacent cam lobes 28, 30,but the outer race 38 is axially misaligned with the block 42 and withthe rest of the needle roller bearing assembly 20.

FIG. 3 illustrates a cage 64 of a roller bearing assembly, particularlya needle roller bearing assembly 60 (FIGS. 4A-5), according to oneembodiment of the present invention. The cage 64 includes a plurality ofslots 68 configured to receive individual rollers, such as needle rollerelements 72. The cage 64 includes a rim portion 76 at each end, axiallybeyond the end of the slots 68. Each rim portion 76 includes at leastone radial projection 80. In the illustrated embodiment, each rimportion 76 includes 3 circumferentially-spaced radial projections 80.The needle roller bearing assembly 60 also includes an outer race 84positioned radially outward of the needle roller elements 72 and axiallycentered on the cage 64 between the radial projections 80 of therespective rim portions 76.

FIG. 5 illustrates the needle roller bearing assembly 60 assembled on acamshaft 90 between two adjacent cam lobes 94, 96 of the camshaft 90.The needle roller bearing assembly 60 is held within a two piececlamp-type block 100. The outer surface of the outer race 84 is heldwithin the block 100 and remains stationary therewith. The needle rollerelements 72 contact the cylindrical outer surface of the camshaft 90directly, but an inner race can be provided between the needle rollerelements 72 and the camshaft 90 in some embodiments. As shown in FIG. 5,the radial projections 80 on the rim portions 76 of the cage 64 preventthe outer race 84 from axial displacement. Thus, the outer race 84cannot slide axially relative to the needle roller elements 72 and thecage 64. The mounting arrangement shown in FIG. 5 enables the bearingassembly 60 to be pre-assembled onto the camshaft 90 so that the outerrace 84 is automatically located in the desired position for beingreceived in the block 100, eliminating the need for an assembler ormachine to position the outer race 84 relative to the block 100 duringassembly.

FIGS. 6A and 6B illustrate a roller bearing assembly, particularly aneedle roller bearing assembly 110 including a cage 114 according to oneembodiment of the present invention. The cage 114 includes a pluralityof slots 118 configured to receive individual rollers such as needleroller elements 122. The cage 114 includes a rim portion 126 at eachend, axially beyond the end of the slots 118. Each rim portion 126includes at least one radial projection 130. In the illustratedembodiment, each rim portion 126 includes two circumferentially-spacedradial projections 130. In the illustrated embodiment of FIGS. 6A and6B, the radial projections 130 are formed by split away sections of therim portions 126 that curve or extend radially outward from thecylindrical wall of the cage 114. The needle roller bearing assembly 110also includes an outer race 134 positioned radially outward of theneedle roller elements 122 and axially centered on the cage 114 betweenthe radial projections 130 of the respective rim portions 126.

One end of the outer race 134 includes a radially inward projection 138extending around the entire circumference of the outer race 134. Theradially inward projection 138 extends over at least a portion of eachof the needle roller elements 122 as shown on the right side of thebearing assembly 110 in FIG. 6B. The radial projections 130 of the cage114 extend radially outward into radial alignment with the inwardprojection 138 of the outer race 134. Thus, the outer race 134 isaxially positioned by the inward projection 138, which is sandwichedbetween the needle roller elements 122 and the radial projections 130 ofthe cage 114. The inward projection 138 of the outer race 134 and theradial projections 130 of the cage 114 also provide a mechanism by whichthe axial alignment of the needle roller bearing assembly 110 is easilycontrolled during installation. Similar to the bearing assembly 60 ofFIGS. 4A-5, the bearing assembly 110 of FIGS. 6A and 6B allows theassembly onto a camshaft so that the outer race 134 is automaticallylocated in the correct axial position for being supported, eliminatingthe need for an assembler or machine to position the outer race 134relative to the support structure (e.g., a clamp-type block) duringassembly.

FIG. 7 is an end view illustrating a roller bearing assembly,particularly a needle roller bearing assembly 150 including a cage 154according to one embodiment of the present invention. The cage 154includes a plurality of slots (not shown) configured to receiveindividual rollers, such as needle roller elements 158 to providerolling bearing support of a camshaft 162. The needle roller bearingassembly 150 also includes an outer race 166 radially outward of theneedle roller elements 158. The outer race 166 contains the needleroller elements 158 and provides a surface on which the elements 158 canroll. A two piece clamp-type block 170 holds the needle roller bearingassembly 150 by contacting an outer surface of the outer race 166. Theblock 170 may be axially positioned between two adjacent cam lobes 174of the camshaft 162, one of which is shown in FIG. 7.

The cage 154 of FIG. 7 is generally ovular or elliptical as opposed tocircular. However, the outer race 166 and the camshaft 162 aresubstantially circular such that the cage 154 does not share a singlecommon axis with the outer race 166 and the camshaft 162. At twocircumferentially opposing sides of the cage 154, a radial gap A iscreated between an outer edge of the cage 154 and an inner edge of theouter race 166. These locations represent the smallest distance acrossthe cage 154. At two different circumferentially opposing sides of thecage 154, a radial gap B is created between an inner edge of the cage154 and an outer surface of the camshaft 162. These locations, whichrepresent the largest distance across the cage 154, are spacedapproximately 90 degrees apart from the locations defining the gaps A.Due to the non-circularity of the cage 154, resistance to axialmisalignment is provided by an interference fit with at least one of theouter race 166 and the camshaft 162. When an interference fit isestablished between the cage 154 and the outer race 166, the bearingassembly 150 of FIG. 7 may be pre-assembled onto the camshaft 162 sothat the outer race 166 is automatically located in the correct axialposition for being supported, eliminating the need for an assembler ormachine to position the outer race 166 relative to the block 170 duringassembly.

FIGS. 8A and 8B illustrate a cage 180 for a roller bearing assembly,particularly a needle roller bearing assembly (not shown) according toone embodiment of the present invention. The cage 180 is substantiallysimilar to the cage 64 illustrated in FIGS. 3-5. The cage 180 includes aplurality of slots 184 for retaining individual rollers, such as needleroller elements (not shown). The cage 180 also includes two rim portions188, each one including one or more radial projections 192, (similar tothe radial projections 80 described above with reference to the cage 64of FIGS. 3-5) which enable precise, automatic positioning of an outerrace relative to a support when pre-assembled onto a camshaft. Inaddition to the radial projections 192, the cage 180 includes springportions 196 extending axially outward from one of the rim portions 188.The cage 180 includes two circumferentially spaced spring portions 196,but other arrangements are contemplated. The cage 180 further includeswear-off portions 200 in the form of studs or bumps on the axial surfaceof the rim portion 188 opposite the spring portions 196. The wear-offportions 200 are illustrated in FIG. 8A as including threecircumferentially spaced rounded studs, but other structures andarrangements are contemplated. The wear-off portions 200 are constructedof a material that is configured to wear away by frictional engagementwith adjacent structure, such as the side face of a cam lobe.

Although the cage 180 of FIGS. 8A and 8B includes spring portions 196 onone end and wear-off portions 200 on the opposite end, otherconfigurations are foreseen that include spring portions 196 on bothends or alternately, wear-off portions 200 on both ends. The springportions 196 enable the cage 180 to be press-fit in between a pair ofcam lobes with a slight amount of axial interference. The wear-offportions 200 are configured to wear down as the camshaft rotates untilthe interference is nearly or completely eliminated and/or a minuteaxial clearance is created. This prevents undue resistance to rotationof the camshaft by the cage 180 bearing axially against the side facesof adjacent cam lobes. Thus, the effort to design and manufacturecomponents with precise axial tolerance is reduced. The spring portions196 may or may not be constructed of a material similar to the bumps 200so that they are also configured to wear down by frictional contact inorder to reduce axial interference and drag on the camshaft.

FIGS. 9A and 9B illustrate a roller bearing assembly, particularly aneedle roller bearing assembly 210 assembled on a camshaft 214 with atwo piece clamp-type block 218. The needle roller bearing assembly 210supports the camshaft 214 for rotation between two adjacent cam lobes222, 224 of the camshaft 214. The needle roller bearing assembly 210includes a cage 228, a plurality of rollers, such as needle rollerelements 232, and an outer race 236. As discussed above with respect toa previous embodiment, an inner race can additionally be provided insome embodiments.

The cage 228 includes slots to position each of the needle rollerelements 232. The cage 228, similar to the cage 64 of FIGS. 3-5, alsoincludes radial projections 240 that position the cage 228 axiallyrelative to the outer race 236. Thus, the bearing assembly 210 of FIGS.9A and 9B may be pre-assembled onto the camshaft 214 so that the outerrace 236 is automatically located in the correct axial position relativeto the block 218, eliminating the need for an assembler or machine toposition the outer race 236 relative to the block 218 during assembly.The cage 228 varies from the cage 64 of FIGS. 3-5 by having an extendedaxial length, so that the cage 228 substantially fills the space betweenthe adjacent cam lobes 222, 224. Thus, the cage 228 is restrained frommoving axially by the presence of the cam lobes 222, 224, and the outerrace 236 is restrained from moving axially by the radial projections 240of the cage 228. Thus, bearing misalignment does not develop during use,and assembly of the needle roller bearing assembly 210 is simplified byproviding an intrinsic mechanism by which the cage 228 and the outerrace 236 are axially positioned with respect to each other.

FIGS. 10A and 10B illustrate a roller bearing assembly, particularly aneedle roller bearing assembly 260 assembled on a camshaft 264 with atwo piece clamp-type block 268. The needle roller bearing assembly 260supports the camshaft 264 for rotation between two adjacent cam lobes272, 274 of the camshaft 264. The needle roller bearing assembly 260includes a cage 278, a plurality of rollers, such as needle rollerelements 282, and an outer race 286. As discussed above with respect toa previous embodiment, an inner race can additionally be provided insome embodiments.

The cage 278 includes slots to position each of the needle rollerelements 282. The cage 278, similar to, the cage 228 of FIGS. 9A and 9B,has an extended axial length, so that the cage 278 substantially fillsthe space between the adjacent cam lobes 272, 274. Thus, the cage 278 isrestrained from moving axially by the presence of the cam lobes 272,274. Rather than providing a direct mechanism between the cage 278 andthe outer race 286 by which relative axial movement is prevented, theouter race 286 is positioned axially by a peripheral wall 290 at eachend that extends radially from the axial end faces of the outer race 286and engages the block 268. Thus, bearing misalignment does not developduring use, and assembly of the needle roller bearing assembly 260 issimplified by providing intrinsic features by which the cage 278 and theouter race 286 are axially positioned with respect to the axiallystationary elements of the camshaft 264 and the block 268.

The embodiments described above and illustrated in the figures arepresented by way of example only and are not intended as a limitationupon the concepts and principles of the present invention. For example,the invention is not limited to use with camshafts, or with internalcombustion engines in general.

Various features of the invention are set forth in the following claims.

1. A roller bearing assembly comprising: a plurality of rollers; a cageincluding a plurality of slots for positioning the plurality of rollers;an outer race positioned radially outside the plurality of rollers andthe cage; and means for retaining axial alignment between the cage andthe outer race provided integrally with at least one of the cage and theouter race.
 2. The roller bearing assembly of claim 1, wherein the cagefurther includes two rim portions axially outward of the plurality ofslots, and at least one of the rim portions includes a radial projectionconfigured to engage an axial end of the outer race.
 3. The rollerbearing assembly of claim 2, wherein the radial projection is a splitaway portion of the rim portion.
 4. The roller bearing assembly, ofclaim 1, wherein the cage further includes axial ends formed withintegral positioning features.
 5. The roller bearing assembly of claim4, wherein the integral positioning features include at least one ofaxial elastically deformable spring portions and wear bumps.
 6. Theroller bearing assembly of claim 1, wherein the outer race furtherincludes one of a radially outwardly extending peripheral wallconfigured to engage a stationary supporting structure and a radiallyinward projection at least partially positioned axially between one ofthe plurality of rollers and a radial projection of the cage.
 7. Theroller bearing assembly of claim 1, wherein the cage is non-circular,and the non-circularity of the cage produces an interference fit with atleast one of the outer race and a shaft supported within the rollerbearing assembly.
 8. The roller bearing assembly of claim 1, wherein theroller bearing assembly is configured to support a camshaft between afirst cam lobe and a second adjacent cam lobe, the cage being configuredto extend axially from the first cam lobe to the second cam lobe.
 9. Aroller bearing mounting arrangement for mounting a roller bearing inposition to support a camshaft for rotation about an axis, the mountingarrangement comprising: a bearing support; and a roller bearingconfigured to be pre-assembled on the camshaft and subsequently mountedin the bearing support, the roller bearing including an outer race, aplurality of rollers, and a cage for positioning the plurality ofrollers, wherein the outer race and the cage of the roller bearing areengaged with each other such that the outer race is automaticallyaxially positioned for mounting in the bearing support when the rollerbearing is pre-assembled on the camshaft.
 10. The roller bearingmounting arrangement of claim 9, wherein the cage includes at least twopositioning features configured to engage at least one of the outer raceand the camshaft.
 11. The roller bearing mounting arrangement of claim9, wherein the cage includes a radially extending projection thatengages an end face of the outer race.
 12. The roller bearing mountingarrangement of claim 11, wherein the radially extending projection is asplit away portion of the cage.
 13. The roller bearing mountingarrangement of claim 11, wherein the outer race includes a protrusionextending radially inward.
 14. The roller bearing mounting arrangementof claim 11, wherein the radially extending projection is one of aplurality of radially extending projections spaced around acircumference of a rim portion of the cage.
 15. The roller bearingmounting arrangement of claim 11, wherein the cage includes a secondradially extending projection engaging an opposite end face of the outerrace.
 16. The roller bearing mounting arrangement of claim 9, whereinthe outer race and the cage are engaged with an interference fit. 17.The roller bearing mounting arrangement of claim 16, wherein the outerrace is circular and the cage is made non-circular to provide theinterference fit.
 18. The roller bearing mounting arrangement of claim9, wherein the cage extends axially a length equal to or greater than alength between adjacent lobes of the camshaft.
 19. The roller bearingmounting arrangement of claim 18, wherein the cage includes an axiallydeformable spring portion extending from at least one end of the cageand configured to compress between two adjacent lobes of the camshaft toestablish an axial interference fit.
 20. The roller bearing mountingarrangement of claim 19, wherein at least a portion of the cage isconfigured to wear away by frictional engagement with the adjacentcamshaft lobes and reduce the amount of axial interference.